Diseases of the eye, specifically age-related macular degeneration (AMD), glaucoma, and diabetic retinopathy affect a large percentage of the population. In part, most of the diseases of the eye are treated by treating one or more symptoms, but failing to address the underlying cause(s) of the disease or condition. These therapies are therefore deficient in one or more aspects, necessitating improved approaches.
In a general sense, the pathogenesis of some eye diseases is similar if not the same as those seen for cardiac diseases and for abdominal aorta conditions. However, the anatomy of the vasculature behind the eye is typically smaller, includes more branches, and includes more sharp angles in the blood flow pathway. Further, the vascular system supplying blood to the eye is closer to the brain and any uncaptured or non-rerouted debris may, upon reaching the brain, cause an immediate stroke.
The use of catheter delivery systems for positioning and deploying therapeutic devices, such as balloons, stents and embolic devices, in the vasculature of the human body has become a standard procedure for treating endovascular diseases. It has been found that such devices are particularly useful as an alternative in treating areas where traditional operational procedures are impossible or pose a great risk to the patient. Some of the advantages of catheter delivery systems are that they provide methods for treating blood vessels by an approach that has been found to reduce the risk of trauma to the surrounding tissue, and they also allow for treatment of blood vessels that in the past would have been considered inoperable.
Obstructive emboli have also been mechanically removed from various sites in the vasculature for years. For example, an embolectomy catheter such as, for example, a “Fogarty catheter,” or variations thereof, has been used to remove clots from arteries found in legs and in arms. These well-known devices are described, for example, in U.S. Pat. No. 3,435,826 to Fogarty, and in U.S. Pat. Nos. 4,403,612 and 3,367,101. In general, these patents describe a balloon catheter in which a balloon material is longitudinally stretched when deflated.
In procedures for removing emboli using such embolectomy catheters or other similar catheters, it is typical to first locate the clot using fluoroscopy. Next, the embolectomy catheter is inserted and directed to the clot. The distal tip of the catheter is then carefully moved through the center of the clot. Once the balloon has passed through the distal side of the clot, the balloon is inflated. The catheter is then gradually, proximally withdrawn. The balloon, in this way, acts to pull the clot proximally ahead of the balloon to a point where it can be retrieved. The majority of procedures using a Fogarty-type catheter repeat these steps until the treated vessel is cleared of clot material.
A variety of alternative emboli retrieval catheters have also been developed, in which various wire corkscrews and baskets must be advanced distally through the embolic material in order to achieve capture and removal. However, removal of emboli using such catheters may give rise to potential problems. One such problem may occur when advancing the catheter through the clot dislodges material to a more remote site where removal may become more difficult or impossible.
The terms proximal and distal, as used herein, refer to a direction or a position along a longitudinal axis of a catheter or medical instrument. Proximal refers to the end of the catheter or medical instrument closer to the operator, while distal refers to the end of the catheter or medical instrument closer to the patient.
The measurement term French, abbreviated Fr or F, is defined as three times the diameter of a device as measured in mm. Thus, a 3 mm diameter catheter is 9 French in diameter.
There are various terms for the parts of the anatomy from the internal carotid artery (ICA) through the ophthalmic artery (OA) to the eye. Hayreh et al. (Brit. J. Ophthal., 46, 65 (1962)), incorporated by reference in its entirety herein, particularly FIG. 4, illustrates the ICA and the OA. Specifically, the OA branches off the ICA in a portion called the “short limb.” An “angle a” is a distinctive turn in the OA near an end of the short limb, and the “long limb” is the portion of the OA before it penetrates into the dural sheath. One skilled in the art will readily recognize that while these are typical or common structures, not all subjects/patients/humans have these exact same structures, e.g., there are human population variations.